1. Field of the Invention
The present invention relates to a self-diagnosis system in an automatic transmission for diagnosing whether or not an electric actuator for switching a shifting position of the automatic transmission is normally driven and controlled.
2. Description of the Related Art
A conventional automatic transmission includes an electric actuator which is driven and controlled by means of a circuit shown in FIG. 8 and described in a bullet of the Japanese Laid-Open Patent Application No. Hei-11-108706, for example.
In the conventional automatic transmission a motor driving circuit 101 shown in FIG. 8 connects in series four switching elements Q1 to Q4 comprising, for example, a power MOSFET between power supply terminals VB and GND to form an H-type of bridge circuit, and is formed by connecting a DC motor M, which is to be driven, between output terminals M+ and Mxe2x88x92 thereof. A row of a PWM pulse is supplied to either the element Q2 or the element Q4 in a normal-reverse electric current path passing through the switching elements Q1 and Q4 or the switching elements Q2 and Q3, while an ON signal or an OFF signal is supplied to the other element Q3 or Q1, so that rotation direction control and speed control would be enabled.
Conventionally, a circuit for self-diagnosing has been mounted in a controlling unit in general in advance, and a pseudo-signal has been generated in the above circuit in such timing that energizing the unit is started so that an operation check would be performed, in order to diagnose whether the rotation direction and the speed of such motor driving and controlling circuit 101 of an automatic transmission are normally controlled or not.
It is required, however, to mount a large number of circuits in order to check all necessary circuits in the structure described above, which leads to an increase in cost. Further, the precision of the self-diagnosis is limited because the pseudo-signal is inputted.
An object of the invention is to provide a self-diagnosis system in an automatic transmission capable of certain self-diagnosis in a simple structure.
An invention according to a first aspect is an automatic transmission comprising: an electric actuator for switching a shifting position by rotating a manual shaft; a shift operating unit for outputting an instruction signal for instructing the above-mentioned shifting position; a rotation position detecting unit for detecting a rotation angle of the above-mentioned manual shaft on the basis of an output signal corresponding to the said rotation angle; and a controlling means for driving and controlling the above-mentioned actuator until a rotation position, which is detected by the above-mentioned rotation position detecting unit in response to the receipt of the instruction signal from the above-mentioned shift operating unit, accords with the instructed shifting position, characterized by comprising: self-diagnosis unit for diagnosing a trouble after driving the above-mentioned actuator to the position over the above-mentioned instructed shifting position for a predetermined amount on the basis of the first instruction signal by the above-mentioned shift operating unit at a starting time of driving an automobile and after driving the above-mentioned actuator in reverse to the above-mentioned instructed shifting position, in accordance with the judgment whether or not an output signal of the above-mentioned rotation position detecting unit corresponds to driving mentioned above.
An invention according to the second aspect is an automatic transmission comprising: an electric actuator for switching a shifting position by rotating a manual shaft; shift operating unit for outputting an instruction signal for instructing the above-mentioned shifting position; rotation position detecting unit for detecting a rotation angle of the above-mentioned manual shaft on the basis of an output signal corresponding to the said rotation angle; and controlling unit for driving and controlling the above-mentioned actuator until a rotation position, which is detected by the above-mentioned rotation position detecting unit in response to the receipt of the instruction signal from the above-mentioned shift operating unit, accords with the instructed shifting position, characterized by comprising: self-diagnosis unit for diagnosing a trouble after driving the above-mentioned actuator to the above-mentioned instructed shifting position on the basis of the first instruction signal by the above-mentioned shift operating unit at a starting time of driving an automobile by varying high or low the duty ratio in driving and controlling the above-mentioned actuator, in accordance with the judgment whether or not an output signal of the above-mentioned rotation position detecting unit corresponds to driving mentioned above.
An invention according to the third aspect is an automatic transmission comprising: an electric actuator for switching a shifting position by rotating a manual shaft; shift operating unit for outputting an instruction signal for instructing the above-mentioned shifting position; rotation position detecting unit for detecting a rotation angle of the above-mentioned manual shaft on the basis of an output signal corresponding to the said rotation angle; and controlling unit for driving and controlling the above-mentioned actuator until a rotation position, which is detected by the above-mentioned rotation position detecting unit in response to the receipt of the instruction signal from the above-mentioned shift operating unit, accords with the instructed shifting position, characterized by comprising: self-diagnosis unit for diagnosing a trouble after driving the above-mentioned actuator to the position over the above-mentioned instructed shifting position for a predetermined amount on the basis of the first instruction signal by the above-mentioned shift operating unit at a starting time of driving an automobile and after driving the above-mentioned actuator in reverse to the above-mentioned instructed shifting position, as well as driving the above-mentioned actuator by varying high or low the duty ratio in driving and controlling the above-mentioned actuator, in accordance with the judgment whether or not an output signal of the above-mentioned rotation position detecting unit corresponds to driving mentioned above.
An invention according to the fourth aspect is the self-diagnosis system in an automatic transmission according to one of the first to third aspect, characterized by carrying out the above-mentioned self-diagnosis between a parking range and a neutral range when the first instruction signal by the above-mentioned shift operating unit is a shifting instruction from the parking range to the driving range as well as driving the above-mentioned actuator to the above-mentioned instructed driving range in accordance with a diagnosis that there is no trouble.
An invention according to the fifth aspect is the self-diagnosis system in an automatic transmission according to one of the first to the fourth aspect, characterized in that the above-mentioned controlling unit controls the above-mentioned actuator so that only the shift to a shifting position on the safety side would be possible regardless of the above-mentioned instructed shifting position, when the above-mentioned self-diagnosis unit judges that there is a trouble.
In the invention according to the first aspect, when the shift operating unit instructs a shifting position, the instructed signal is inputted to the controlling unit, which drives and controls the actuator so that the manual shaft would be driven to rotate to the instructed shifting position. When the rotation position of the manual shaft, which is detected by the rotation position detecting unit, accords with the shifting position instructed by the above-mentioned shift operating unit at that time, driving and controlling of the actuator are stopped and the manual shaft stays at the instructed shifting position.
In such automatic transmission, a self-diagnosis unit can self-diagnose a trouble after driving the above-mentioned actuator to the position over the above-mentioned instructed shifting position for a predetermined amount on the basis of the first instruction signal by the above-mentioned shift operating unit at a starting time of driving an automobile and after driving the above-mentioned actuator in reverse to the above-mentioned instructed shifting position, in accordance with the judgment whether or not an output signal of the above-mentioned rotation position detecting unit corresponds to driving mentioned above.
Therefore, there is no need to provide a special circuit for diagnosis, which means a simple circuit structure capable of reduction of a cost, while the self-diagnosis in driving and controlling the actuator depends on no pseudo-signal, so that an accurate self-diagnosis can be achieved.
In the invention according to the second aspect, when the shift operating unit instructs a shifting position, the instructed signal is inputted to the controlling unit, which drives and controls the actuator so that the manual shaft would be driven to rotate to the instructed shifting position. When the rotation position of the manual shaft, which is detected by the rotation position detecting unit, accords with the shifting position instructed by the above-mentioned shift operating unit at that time, driving and controlling of the actuator are stopped and the manual shaft stays at the instructed shifting position.
In such automatic transmission, a trouble can be self-diagnosed after driving the above-mentioned actuator to the above-mentioned instructed shifting position on the basis of the first instruction signal by the above-mentioned shift operating unit at a starting time of driving an automobile by varying high or low the duty ratio in driving and controlling the above-mentioned actuator, in accordance with the judgment whether or not an output signal of the above-mentioned rotation position detecting unit corresponds to driving mentioned above.
Therefore, the circuit structure can be simplified and the cost can be reduced, while the self-diagnosis in driving and controlling the actuator does not depend on pseudo-signal, so that an accurate self-diagnosis can be achieved.
In the invention according to the third aspect, when the shift operating unit instructs a shifting position, the instructed signal is inputted to the controlling unit, which drives and controls the actuator so that the manual shaft would be driven to rotate to the instructed shifting position. When the rotation position of the manual shaft, which is detected by the rotation position detecting unit, accords with the shifting position instructed by the above-mentioned shift operating unit at that time, driving and controlling of the actuator are stopped and the manual shaft stays at the instructed shifting position.
In such automatic transmission, a self-diagnosis unit can self-diagnose a trouble after driving the above-mentioned actuator to the position over the above-mentioned instructed shifting position for a predetermined amount on the basis of the first instruction signal by the above-mentioned shift operating unit at a starting time of driving an automobile and after driving the above-mentioned actuator in reverse to the above-mentioned instructed shifting position, as well as driving the above-mentioned actuator by varying high or low the duty ratio in driving and controlling the above-mentioned actuator in accordance with the judgment whether or not an output signal of the above-mentioned rotation position detecting unit corresponds to driving mentioned above.
Therefore, the circuit structure can be simplified and the cost can be reduced, while the self-diagnosis in driving and controlling the actuator does not depend on pseudo-signal, so that an accurate self-diagnosis can be achieved.
In the invention according to the fourth, in addition to the effect of the invention according to one of the first aspect to third aspect, the self-diagnosis of a trouble can be carried out between a parking range and a neutral range even when the instruction signal is a shifting instruction from the parking range to a driving range, so that a pattern of the diagnosis would be same as the case that the first instruction signal by the shift operating unit is the neutral range, which enables the control to be simplified.
In the invention according to the fifth aspect, in addition to the effect of the invention according to one of the first aspect to the fourth aspect, the controlling unit controls the actuator so that a shifting position would be on the safety side regardless of the instructed shifting position, when the self-diagnosis unit judges that there is a trouble.
Therefore, when it is judged in the self-diagnosis that there is a trouble, it is possible to set the shifting position on the safety side, that is, to fix the shifting position to the neutral position, for example, so that the safety can be ensured.